或 c1=∑xy,k=1,2…,n+1 或矩阵形式: ∑x2∑x2n.∑ ∑xy ∑xy n+1 y• 或 • 或矩阵形式： 1 2 2 1 1 1 1 ( ) , 1,2, , 1 n L L n j k n k i j i i j i i x c x y k n + + − − + − = = =   = = + 2 2 1 1 1 1 1 1 2 1 1 1 2 1 1 1 1 0 1 1 1 . . . . . . . . . . . L L L L n n n n i i i i i i i i i L L L n n n i i i i i i i L L L n n i i i i i i x x x x y c x x x y c c x x y − = = = = − − − = = = + = = =               =                      